Fuel-injection control device



l G. AMERY FUEL-INJEcT'o'N CONTROL DEVICE Filed Aug. 15, 1938 'March 1"'4, 1939.

Patented Mar. 14, 1939 UNITED STATES PATENT lOFFICE l 23150574 FUEL-INJECTION CONTROL DEVICE Gmeorge Amery, London, England Application August 15, 193s, serial No. 225,024

In Great Britain August 25, 1937 s claims.

This invention comprises improvements in or relating to fuel-injection controlling devices for internal-combustion engines.

The invention is applicable in the case of injection systems in which a fuel-nozzle isprovided having 'a nozzle-valve, a valve-closing piston and means to apply valve-closing fluid presf Ysure thereto so as to yclose the nozzle-valve while orifice, a fuel passage thereto, a nozzle-valve for closing said nozzle orifice but capable of being opened by fuel pressure, a valve-closingpiston;

means for admitting fluid under pressure to said..1 valve-closing piston and an auxiliary cut-oil:` Yvalve opened to the same pressure as the valve-closing piston for closing the said fuel passage.

The auxiliary cut-off valve when closed may serve to open a communication between a drain passage and the portion of the fuel passage which lies between the cut-olf valve and the nozzlevalve.

In a preferred construction the fuel-nozzle comprises a valve-closing pressure chamber coaxial with the nozzle-valve, within which the valve-closing piston operates, and the auxiliary cut-olf is provided with a valve-closing piston vwhich is located in the said pressure chamber.

Y The following i's a description, by way of exv ample, of one fuel-injection system and fuel-nozzie for use therewith, reference being made to theaccompanying drawing, in which:

'Figure 1 is a diagram of a fuel-injection system, and

Figure 2 is a longitudinal section 'through a` fuel-nozzle.

Referring to Figure 1, 'this shows in diagram-` (c1. a99-1cm) the end of the distributor casing plunger extends to the interior of the casing and Fuel is drawn from a tank by the pump in the casing through an inlet pipe 63 and is'delivered by the pump under pressure to a delivery box 52. The delivery pressure of the pump is controlled by the governor-in the casing oper- 6 ating -upon a relief valve. The relief valve acts in a chamber connected to the delivery box by the pipe 96. Pipes 95 convey fuel oil to valves in the distributor I5, which valves are operated bya cam in the distributor and are opened in their cor- 10 rect sequence to deliver fuel oil through the distributor pipes 94. A plunger 83 projects from |5. This is capable of moving the distributor cam axially l so as to vary the time during which pressure is applied in each ofthe pipes 94. The plunger 83 is connected to a hand control or accelerator, not shown in the drawing, for determining the power output of the engine with which the injection systemv is employed.

The injectors |00 are constructed as shown in Asection in Figure 2. Each injector. comprises a connection for the distributor pip'es 94, a second connection for a drain`103 and a third connec- .25 tion for a pipel02, which isgconnected directly tothe delivery box 52 of the pump and therefore is continuously maintained Ifull of fuel oil under injection pressure. The fuel oil which is actually injected into the engine .is delivered by the pipe |02 and the oil periodically put under pressure in the pipes 94 is not injected into the engine but is used for controlling the opening and closing of a needle-valve |20 in the injector body |00.

In the injector .body` there is a valve chamber |2| to which the oil in the pipe 94 has direct access. The valve-closing pressure-chamber |2| contains a needle-valve closing-piston |22 which bears, by means of a stem |23, on the back of a push-rod |43 which bears on the needle-valve |20. 40

`Closing pressure on the needle-valve is further exerted by means of a spring |24. 'I'his spring determines the minimum pressure of injection. 'I'he drain pipe |03V is connected to the space |25 in which the spring |24 Works and it will be s. .n 45 that any leakage of fuel oil past the piston |22 enters this space and therefore such leakage is carried away by the drain which returns it to the tank |0| through the pipe |04 (Figure 14).

The strength of the spring |24 may be ad- 50 justed by means of a screwed plug |26 in the injector body |00.

The pressure chamber |2| is formed in a plug |21 which abuts against the back of the screwed plug |2|i`and is a close fit in a bore in the ina rector body loo. The plug |21 is itself hem down i by a second plug |28 and the .whole is pressed rmly together by a cap T|28 to which the fuel oil delivery pipe |02 is connected. In the outer plug |28 is a seatingv|3| for an auxiliary cut-off `valve |30.. The auxiliary cut-off valve |30 has through sprayerapertures in the nozzle |35. The needle-valve and nozzle may be of any construction, such as the construction whichis commonly used in fuel-injection nozzles whereby pressure around the needle valve tends to lift it and permit fuel to be sprayed into the engine cylinder. In the present case the lifting `of the needle-valve will take place against the action of the spring Returning tothe auxiliary cut-oil' valve |30' this has agroove |36 around its stem whichreg'- isters with the passage |33 when the valve is closed and communicates with a longitudinal groove |31. The groove |31 serves when the auxiliary cut-off valve is closedto connect the pas- ,sagev |33 with a drain chamber |38 formed in the outer plug |28. The drain chamber communif cates by a radial passage |59 with a 'groove |60 around the plug |28 and this groove in turn communicates with a longitudinal groove |41 inthe outside of the plug |21 which contains the valveclosing pressure-chamber |2I. The drain groove |4| communicates, by means of a slot |42 lcut in the end of the screwed plug |26, with the chamber |25 and thence with the drain pipe |03. Thus when the auxiliary cut-off valve |30 is closd the nozzle |35 will be connected by the passage |34 with the drain |03 and. pressure will be relieved from the space around the needle-valve |20.

.In operation, as long as pressure is maintained in the pipe 94, this pressure will be 'communicated to the valve-closing pressure-chamber 2| and by means of the'pistons |22, |32, both .the needlevalve |20 and the auxiliary cut-off valve A|30 will be held closed. The distributor '|5'is so arranged that, when iniection is to take place in anyone of the fuel injectors |00, it cuts o the supply of fuel'pressure lfrom the pipes 34 and connects them to a drain |06 (Figure l). A pressure retaining valve i's preferablyprovided between the casing and the drain U06 so as to ensure that a low pressure, much less than the injection pressure, say about 50 lbs. per square inch, is maintained in the pipes 94 notwithstanding their connection to the drain. 'I'his low pressure, which persists in the chamber` |2|, does not suffice to prevent the pressure in the pipe |02 from opening the auxiliary cut-oi valve |30. Consequently the passage |34 is disconnectedfrom the drain chamber |38 and connected to the fuel pressure, which immediately lifts the needle-valve |20 and causes iniection to commence. .As soon as the distributor I acts to reapply pressure in the control chamber |2| the needle-valve |20 is closed by the action of the closing piston |22 (which is of larger area than the opening piston on the needle-valve) and this closure takes place against the full pressure of the fuel oil in the passage |34. This closing movementis assisted by thek spring |24 and takes place very quickly.' The auxiliary cut-oil' valve |52 is almost immediately afterwards moved to its closed position, seats itself on the seating |3| and opens the channel |34 to the drain |03.

The result is that the needle-valve is closedv against the full fuel pressure but when it is closed the fuel pressure is held lup at the seat I 3|, the pressure in passage |34 is released to atmosphere -or thereabouts epd there is therefore no tendency of the fuel oil to dribble into the engine cylinder after the needle-valve is closed. If the needlevalve were closed by releasing pressure from the passage |34 and merely allowing it to close by the spring |24, the fall ofpressure at the seating of the needle-valve would prevent vthe fuel from being properly sprayed into the ,engine cylinder during the interval of time while the valve is closing.' If, on the other jhand, the valve were closed against the fuel pressure by the action of the closing piston |22 and the auxiliary cut-oi'f right up to thetime the needle-valve closes without any risk of dribbling afterwards. v

lReferring again to Figure 1 it will be observed there is asecond drain from the casing lvlv to the fuel tank |0I, .the object ofwhich is to permitl the escape of-any oil whichmay leak past thepump plungers in the casing The result of maintaining a residual pressure in thedistributor pipes 94 as hereinbefore referred to is to ensure that' thel operation of. the

pistons'l22, |32 is prompter when thefuel pressure is applied.

I claim: A

l. -In a fuel-injection system which comprises a fuel-nozzle, a nozzle-valve therefor, a valve-closing piston and means to apply valve-closing uidpressure thereto so as to close the nozzle-valve while the fuel-pressure at the nozzle-valve is stili maintained, the provision of an auxiliary cut-oil.' valve actuated by the valve-closing pressure for putting off vfuel pressure from the nozzle-valve upon the said valve being closed.

2. Amel-injector comprising in'combinatio'n a nozzle, a fuel passage thereto, a nozzle-valve for closing said nozzle but capable of being opened by fuel pressure, a -valve-closiug piston, means for admitting fluid under pressure to said valveclosing piston and. an auxiliary cut-off valve operated by the same pressure as the valve-clos- (soy ing piston for cutting off the said fuel passage from the fuel pressure.

3. A fuel-injector as claimed in claim 2, wherein the auxiliary cutoff valve when closed serves -to open communication between a drain passage and the portion of the fuel passage which lies between the cut-oil? `valve and the nozzle-valve.

4. A fuel-injector as claimed in claim 2, com# prising a valve-closing pressure-chamber co-axial withHthe'nozzle-valve, within *which the valveclosing piston operates, and thefauxiliary cut-olf valve is provided with avalve-closingpiston which is located i n the said pressure chamber..

5. A rua-injector as claimed in'claim '2, having additional spring means operatively connected to 75,'

the nozzle-valve for assisting in closing the same.

6. A fuel-injector as` claimed in claim 2; comprising a valve-closing pressure-chamber co-axlal with the nozzle-valve withidwhich the valveclosing piston operates, a spring chamber interposed between said pressure chamber and' the nome-valve, a spring in said chamber for assisting in closing said nozzle-valve and a drain from said spring chamber to carry away leakage from the nozzle-valve and closing piston.-v

7. A fuel-injector as claimed in claim 2, comprising' a valveclosingpressurechamber co-axial with the nozzle-valve within which .the valve-closing piston operates, a spring chamber interposed between said pressure chamber and the nozzlevalve, a spring in said chamber for assistina'in closing said nome-valve, a drain from said spring chamber to carry away leakage from the nozzlev valve and closing piston, wherein the auxiliary cut-oit valve is provided with a valve-closing piston located in said pressure chamber and the aux l iliary valve is provided with means whereby when it is closed it opens communicationv between the said drain and the portion of the fuel passage which llies between the cut-oi! valve and the nozzie-valve.

8. A fuel-injector as claimed in claim 2; having additional spring means operatively connected to the nozzle-valve for assisting in closing the same .and means for adjusting the force of said spring means. f

' GEORGE AMERY. 

